The invention relates to a method for inducing oxygen scavenging within paperboard packaging structures using ultraviolet light to activate the scavenging material. An ultraviolet lamp is placed in close proximity to a blank along the horizontal chain or line following carton bottom formation and prior to filling a carton or blank with product. An alternative form of this invention is to activate the package using a separate apparatus prior to placement on the filling machine.
In the past, oxygen scavenging polymer materials have been controlled by ultraviolet light, which is used to initiate the scavenging reaction. These materials have been placed by extrusion or otherwise, into multilayer structures.
U.S. Pat. No. 5,529,833, Speer et al, discloses a multilayer structure having an oxygen scavenger material incorporated therein. The material may be a distinct layer or may be combined with a heat-seal layer, a barrier layer or a tie layer in the laminate. Nowhere is there a discussion or suggestion of activating the oxygen scavenging material by ultraviolet radiation in the filling machine chain or line following carton bottom formation and prior to filling a produced package or carton.
U.S. Pat. No. 6,039,922, Swank et al, discloses a method for sterilizing a carton using UV light in combination with hydrogen peroxide. Nowhere is there a discussion or suggestion of activating an oxygen scavenging material.
It is an object of the present invention to provide a method of optimally activating oxygen scavenger materials with UV light in and during carton formation.
It is a further objective of the present invention to provide a method of activating oxygen scavenger materials by exposure to ultraviolet lamps prior to, or during the chain or filling line for cartons.
It is a further objective of the present invention to provide a method of activating oxygen scavenger materials in a filling machine after carton bottom formation and before filling a carton with product.
It is a further objective of the present invention to provide a method of activating oxygen scavenger materials in a preliminary step prior to carton formation and filling on a filling machine.
The shortcomings of the existing carton structures which contain only passive oxygen barriers are overcome by the following optimal methods of activating an oxygen scavenger material contained within a packaging structure. The packaging structure containing the scavenging material is produced into a blank for carton formation. In a first embodiment, after the bottom seal is produced in a gable-top type carton, the carton is exposed to ultraviolet radiation in the filling machine chain or line following carton bottom formation. In a second embodiment, the carton blank is opened into a tube and is exposed to ultraviolet radiation and activated using a separate apparatus prior to placement on the gable-top filling machine.